Fuel Octane

[scruffboy]

These are the recommended fuels as printed in the "Supra Handbook" that is so popular on the internet:

Fuel type: 7M-GE engine: For optimum engine performance, Toyota recommends using premium type unleaded gasoline with an octane number of 95 or higher (Research Octane Number).

If such premium type cannot be obtained, you may use unleaded gasoline with an octane number as low as 91.

7M-GTE engine: Unleaded gasoline with an octane number of 97 or higher (Research Octane Number).

I have never seen an American Gas Station that sells octanes this high. Is this a misprint, or does Japan sell fuel processed to this level? I do not want to put a premium octane fuel in my engine if it is not going to be totally combusted. I do not think my car produces compression levels that warrant such a high octane level. Am I safe using 89 Octane fuel in my Non-Turbo 1989 Supra? What is the low down on the type of fuel for Supras?

Scruffboy